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Former Member

PCo 2.0 does not recover after "System is too busy" error.

We run PCo 2.0.1.8 with multiple agents (OPC-DA 2.05a --> MII 12.1.6.Build(91)).

Sometimes our MII-Server is under heavy load and is not able to process PCo messages anymore. Therefore one PCo agent stops working and logs this message:

"System is too busy. Incomming message processing is halted until the system becomes less busy."

The other agents stop working as well. They never recover and start sending messages again.

It is not about retrying to a send old message again. We set "Maximum Retry Attempts" to 3 and "Retry Interval" to 1.

It is about sending new messages after OPC items changed. Our OPC servers change values at least once a minute, which should result in new messages.

Any suggestions to solve this issue?

Regards,

Martin

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2 Answers

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    Former Member
    Aug 26, 2010 at 01:55 PM

    Martin,

    Are you investigating why your MII server is getting overloaded? MII 12.1 can use NW CE's clustering ability to do load balancing. Just a thought....

    You may want to increase your retry interval since it takse only a few seconds until PCo stops attempting sending the notification (3 tries, at 1 second after failure found may be too impatient for dealing with a slow overloaded MII server).

    PCo was designed to be more of a push technology than a constant pulling application. If you need values to be updated in the time frame you mentioned about your OPC server, you may want to use UDS instead. PCo is geared more toward event notification based on expression evaluation (e.g. cylinder temp > 90F or line yield < 30). I am not sure if you want to be sending out alerts every minute with PCo.

    Regards,

    Kevin

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    • Former Member Former Member

      Kevin,

      the Failed Message Persistence is set to KeepLast, because we don't need outdated notifications. PCo/MII has to process the notification in time or not at all. But I changed the Retry Interval from 1 to 5 seconds and reduced the Maximum Retry Attempts from 3 to 2, to give MII some more time to recover. Maybe it helps.

      You are right about the Trigger Type. In this specific case it is set to Always. All the agents are sending to the same MII. PCo has its own machine, without any other processes (OPC, NetWeaver/MII, Database) running on it. (max. 1.7 of 6 GB RAM full, max. 10% CPU used).

      Regards,

      Martin

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    Former Member
    Aug 26, 2010 at 09:23 PM

    How many messages are you sending per minute to MII? It seems unlikely that you could overload the web server, which should be able to handle a very large amount of URLs at any one time, each on its own thread. What OS/DB are you running MII on?

    Also - are you trying to create a simple data historian with MII to a database? We never recommend this approach. The data historian market is mature and there are many good ones out there.

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    • Former Member

      John,

      the reason for the overload was not the amount of PCo notifications (max. 40 per Minute). We changed a lot in the MII-System (HW, SW, OS) so that this will probably never occur. But the question was why PCo never recovered from the "System too busy" error.

      And you are right about the "simple data historian", but this is only a small part of the MII project. I can't tell the customer to buy another Non-SAP software. This would probably embarrass the SAP guy who sold the MII license. I just have to make it work using PCo and MII.

      Regards,

      Martin